1. Field of the Invention
The present invention relates to a magnetic transfer apparatus for magnetically transferring the data borne on a master medium to a slave medium.
2. Description of the Related Art
A magnetic transfer method is a method comprising the steps of: bringing a master medium, on which a transfer pattern has been formed, into close contact with a slave medium, which has been provided with a magnetic recording portion for receiving the transfer, to form a conjoined body; and applying a transfer magnetic field to the conjoined body so as to transfer and record the magnetic pattern corresponding to the transfer data (such as servo data) onto the slave medium.
This magnetic transfer method has been described in Japanese Unexamined Patent Publication Nos. 63(1988)-183623, 10(1998)-40544, and 10(1998)-269566, for example.
However, when performing magnetic transfers according to the magnetic transfer method described above, the surface of the master medium becomes littered with dust and other debris that becomes attached thereto through the repeated usage thereof. This dust and debris can consist of foreign matter originating in the surrounding environment, which becomes lodged between the master and slave medium, or material originating from the master and/or slave medium, which is scraped from either surface thereof, respectively, when said master medium and said slave medium are brought into close contact.
If a magnetic transfer is performed when there is dust or other debris attached to the surface of the master medium, adequate contact between the area of the surface of the master medium centering on the dust or debris attached thereto and the surrounding vicinity thereof and the corresponding area of the slave medium cannot be ensured; whereby a pattern of a predetermined signal level cannot be transferred, and the transfer quality becomes deteriorated thereby. For cases in which the recorded signal data is a servo signal, there is a problem in that an adequate tracking function cannot be obtained, and the reliability of the transfer is deteriorated thereby.
By repeatedly bringing a master medium, onto the surface of which dust and/or debris has become attached, into close contact with slave mediums, the attachment strength of the dust and/or debris to the surface of the master medium is heightened; whereby deficiencies in pattern transfer of the same or greater magnitude are repeated during the performance of magnetic transferences to slave mediums subsequently brought into close contact with said master medium, and said dust and/or debris becomes the cause of multiple faulty products. Further, the surface of the master medium becomes deformed by this attached debris, and a problem arises in that the proper functionality thereof is lost.
Further, in this regard, cleaning technology, wherein a cleaning disk to which a cleaning pad has been attached is pressed against the surface of the master medium to remove dust and debris that have become attached thereto has been proposed as described in Japanese Unexamined Patent Publication No. 2000-285367, for example. Further, removal of attached dust and debris by washing can also be considered.
Still further, for cases in which the slave medium is a disk shaped medium such as a hard disk or a high-density flexible disk, a transfer magnetic field is applied to a conjoined body formed of a slave medium and a master medium(s) brought into close contact with one or both surfaces of the slave medium, by use of a magnetic field generating means employing an electromagnetic apparatus or a permanent magnet apparatus (es), which is disposed on one or both sides of the conjoined body. An important issue regarding the improvement of the transference quality occurring in the magnetic transference relates to the bringing into close contact the master medium and the slave medium so that there is no gap whatsoever therebetween. That is to say, if there are deficiencies in the contact between the respective surfaces of the master medium(s) and the slave medium, regions on the slave medium onto which the magnetic transfer has not been effected occur; whereby the quality of the transferred and recorded signal is deteriorated due to the occurrence of signal omissions in the magnetic data transferred to the slave medium. For cases in which the recorded signal is a servo signal, a problem arises in that an adequate tracking function cannot be obtained, whereby the reliability of the magnetic transfer is deteriorated.
Generally speaking, with regard to magnetic storage mediums, there is a demand for increased storage capacity and low cost. Further desired are so-called high-speed access mediums, which are capable of advantageously reading out the data of a desired location in a short time. Examples of these mediums include hard disks and HD (high-density) flexible disks; so-called tracking servo technology, wherein the magnetic head accurately scans a narrow width track to achieve a high S/N ratio, plays a substantial role in attaining the high storage capacity thereof. A servo signal, address data signal, replay clock signal, etc., used for tracking within a certain interval occurring in one rotation of the disk are “preformatted”, that is, recorded on the disk in advance.
The magnetic head is set so as to be capable of reading out the preformatted signals and correcting its position thereby, whereby the magnetic head can accurately scan the track. According to the currently available preformatting technologies, one disk at a time, one track at a time is recorded by use of a specialized servo recording apparatus.
However, because the servo recording apparatuses are expensive and the preformatting operation consumes a considerable amount of time, this process accounts for a significant portion of the manufacturing costs incurred in producing preformatted disks; a reduction of said costs is desirable.
Meanwhile, methods of utilizing magnetic transfer to achieve this objective, not writing one preformatting track at a time, have been proposed. Magnetic transfer methods have been proposed in, for example, Japanese Unexamined Patent Publication Nos. 63(1988)-183623, 10(1998)-40544, and 10(1998)-269566. According to these magnetic transfer technologies, because a master medium and a slave medium are brought into close contact to form a conjoined body, and a transfer magnetic field is applied thereto, whereby a magnetic pattern corresponding to the data (e.g., a servo signal) borne on the master medium is transferred to the slave medium, the preformatting can be performed without changing the relative positions of the master medium and the slave medium-that is, while the two media remain stationary; not only is it possible to perform an accurate recording of the preformat data, it becomes possible to do so in an extremely short time.
Further, for cases in which the slave medium is a disk shaped medium such as a hard disk or a high-density flexible disk, a transfer magnetic field is applied to a conjoined body formed of a slave medium and a master medium(s) brought into close contact with one surface or both surfaces of the slave medium, by use of a magnetic field generating means employing an electromagnetic apparatus or a permanent magnet apparatus(es), which is disposed on one or both sides of the conjoined body. When the transfer magnetic field is applied, in order to apply the magnetic transfer current in the track direction of the slave medium, the conjoined body, formed of the master medium(s) and the slave medium that have been brought into and maintained in close contact, or the magnetic field is rotated relative to each other, whereby a magnetic pattern is transferred to the track on the entire circumference of the disk shaped slave medium.
An important issue regarding the performance of this magnetic transfer relates to the accurate positioning of the slave medium and the master medium. In particular, regarding the slave medium, which is a hard disk or the like, the rotational center of the drive apparatus into which the slave medium is to be loaded after a magnetic pattern has been transferred thereto must be accurately aligned with the center position of the magnetic pattern that has been transferred and recorded onto said slave medium. In this regard, it is difficult to manufacture the master medium so that the center of the pattern of the transfer data and the center position of the body of the master medium itself are accurately aligned; for example, there are cases in which even if a hole for determining the center position has been formed in the master medium, the accuracy of the process whereby said hole has been formed has been insufficient.
Regarding the points described above, an image apparatus wherein the positions of the master medium and the slave medium are determined when said master and slave medium are brought into close contact is described in Japanese Unexamined Patent Publication No. 11 (1999)-175973. More specifically, after first setting the slave medium into a setting flange, a master medium, which is provided with a transparent portion having a marker corresponding to the transfer pattern is loaded thereon, and the position of the master medium is adjusted while the position of the marker and the position of the slave medium are observed by use of an image apparatus, so as to be aligned, and then said master and slave medium are brought into close contact.
Here, when the master medium is to be cleaned, the master medium is removed from the magnetic transfer apparatus, and each type of dust and debris attached to the surface thereof is removed; because the master medium must then be again loaded into the magnetic transfer apparatus, a problem arises in that the operation rate of the transfer is reduced due to the difficulty of properly positioning the master medium.
In particular, because the accuracy obtained by a simple positioning is inadequate due to the fact that the transfer pattern, such as a servo pattern or the like, formed on the master medium becomes finer as the recording capacity thereof is increased, and the ability of the predetermined functions thereof to be accurately performed cannot be ensured if the center position of the transfer pattern and the rotational center of the slave medium are not aligned with a high degree of accuracy, a troublesome operation wherein the servo pattern or the like must be observed by use of a measuring microscope or the like and aligned is required. Therefore, because time is consumed in removing and reloading the master medium, production inefficiencies arise.
Further, there is also a fear that airborne dust will become adhered to the surface of the master medium or that dust adhering to the hands of an operator or to components of the apparatus coming into contact with the master medium will become transferred to the surface of the master medium when the master medium is being conveyed or loaded after the cleaning process has been performed thereon; thus causing deficiencies in the magnetic transfer.
The present invention has been developed in view of the foregoing problems, and it is an objective of the present invention to provide a magnetic transfer apparatus wherein the exchange of the master medium can be performed easily, the transfer operation rate is improved, and more efficient production is realized.
Further, according to current magnetic transfer apparatuses, in order to improve the contact between the master medium and the slave medium, a pressing means is employed for applying pressure to the master medium so as to press the slave medium against the master medium, and for removing the air between the respective contact surfaces of the master and slave mediums by use of suction so as to reduce the quantity of air remaining therebetween.
At this time, a lower chamber, in which the master medium is held in position, and an upper chamber, in which the slave medium that is to be pressed against the master medium is held in position are provided; wherein the upper surface of the lower chamber and the lower surface of the upper chamber are provided with a sealing element such as an O-ring by which both of said surfaces are brought into close contact and hermetically sealed. In this configuration, if the degree of vacuum within the interior is increased, the sealing element deforms, the pressure increases, and the degree of vacuum and the contact pressure cannot each be controlled independently. Therefore, an optimal degree of vacuum and an optimal contact pressure cannot be obtained, leading to contact deficiencies, and causing a deterioration of the durability of the master medium.
That is to say, if the pressure exerted by the slave medium against the master medium is increased, a problem arises in that the micro uneven pattern, which corresponds to the transfer data, formed on the master medium becomes more prone to being damaged, and the durability of the surface thereof is also adversely affected. Further, if the degree of vacuum is reduced, it becomes more likely that the quantity of air remaining between the contact surfaces will increase.